Variable-speed drive system

ABSTRACT

A variable-speed drive system comprising at least one device movable along a guide path, wherein a rotating drive member is provided which is rotated at a constant speed and rolls on a bearing surface associated with said guide path. Means are provided to vary the rolling radius of the rotating member on the bearing surface in dependence upon the position of the moving device along the guide path so that the linear speed of said device may vary according to a predetermined law. The rotating member may be a pulley having a slidable flange and associated with a constant width bearing surface or a one-piece pulley associated with a variable section bearing surface.

United States Patent Inventor Appl. No.

Filed Patented Assignee Priority VARIABLE-SPEED DRIVE SYSTEM 13 Claims,9Dr-awing Fig.

U.S.Cl. 198/110, 74/230.16, 198/16 Int. Cl ..B65g 23/06, 865g 23/08, 865g 23/30 Field of Search 198/16, 110, 135;74/l90, 192,217,23016; 104/25; 198/76 Ill 5 41 f 2 7 I 7 f m t... :1 2a

1 O I I a:

l 0 e. 3 e a Primary Examiner-Joseph Wegbreit Assistant Examiner-Bruce H. Stoner, Jr. Attorney-Young & Thompson ABSTRACT: A variable-speed drive system comprising at least one device movable along a guide path, wherein a rotating drive member is provided which is rotated at a constant speed and rolls on a bearing surface associated with said guide path. Means are provided to vary the rolling radius of the rotating member on the bearing surface in dependence upon the position of the moving device along the guide path so that the linear speed of said device may vary according to a predetermined law. The rotating member may be a pulley having a slidable flange and associated with a constant width bearing surface or a one-piece pulley associated with a variable section bearing surface.

PATENTED M1824 |97i SHEET 1 BF 3 QTTys,

PATENTEDAUGZdlQ/l 3.601.246

SHEET 3 OF 3 QUEs 0000/3 ATrys.

VARIABLE-SPEED DRIVE SYSTEM This invention relates to a variable-speed drive system comprising at least one device movable on and driven along a guide path, the connecting means between the device and the guide path being such that programmed speed variations of the moving device are possible. It is more particularly an object of this invention to enable to moving device to be moved at a variable speed by constant-speed drive means, speed variation being dependent upon the position of the moving device on the guide path.

The moving device according to the invention can be used either alone or together with other similar devices disposed on the same guide path, and the resulting drive system can be used either alone or in association with other similar systems or in association with conveyors, inter alia of the variablespeed kind. 7

According to the invention, a variable speed drive system comprising at least one device movable along a guide path is characterized in that the system comprises a rotating drive member which rolls on at least one bearing surface associated with the guide path; and means are provided to vary the rolling radius of the rotating member on the bearing surface in dependence upon the position of the moving device on its guide path. Of course, if the rotating member driving the moving device runs at a constant speed, varying the rolling radius of such member on the bearing surface is a means of varying the speed at which the moving device moves along the guide path.

The invention provides various means for varying the rolling radius. Preferably, the rotating member driving the moving device is a pulley having a fixed flange and a flange which can slide along the pulley axis of rotation and which is resiliently restored towards the fixed flange; and the bearing surface associated with the pulley is disposed at a variable distance from the pulley axis but is of uniform width. According to a second feature,'the rotating member driving the moving device is a one-piece pulley having flared flanges; and the bearing surface is of variable width, means being provided to engage the pul ley with such surface along the path.

There are many possible uses for the drive system according to the invention, and the uses given hereinafter are given solely as nonlimitative examples.

The system according to the invention can be used e.g. to move a machine element, inter alia to move a tool of a machine tool, in which event the moving device serves as a support for such'tooLPossible uses of the speed variations are e.g. a rapid tool return after its working movement or a cutting rate adjusted to depth of cut or acceleration in an idle move ment between two consecutive working movements etc.

A system according to the invention is also of use for conveyi ng articles along a path where accurately programmed speed variations are required. This occurs, for instance, when articles being processed are required to move pasta series of working stations with a different treatment time at each station, as is the case e.g. with articles moving along an automatic painting line on which pickling, degreasing, painting and dryingare operations each taking up different amounts of time. In this case the moving device can have a support or holder for the workpiece.

Another use of the system according to the invention is to maintain the balance of unstable fragile articles being carried on a conveyor whose speed varies at various places, as is the case with glass bottles, plaster and ceramic statuettes etc. moving along a powered roller conveyor whose speed alters along its path. The speed of the moving device according to the invention can be programmed to be always equal to the speed of the conveyor-home articles over the whole length of the conveyor path, and the device can have e.g. an article-indexing finger, a gripper clampingthe top of the article or a finger engaging in the bottleneck etc.

Another use deriving directly from the use just described is as a handrail associated with a travelator, inter alia a pedestrian-accelerating belt, whose speed varies at various parts of its travel; pedestrians on a conveyor of this kind need to have a support at an appropriate height so that they can keep their balance or, where necessary, regain the same. For a lasting grip and for the safety of passengers, a pedestrian support of this kind must always move at the same speed as the particular part of the conveyor being used by the pedestrian.

Other features of the invention will be disclosed by the following description.

Various embodiments of the system according to the invention are shown in the accompanying exemplary nonlimitative drawings wherein:

FIG. 1 is a diagrammatic view in elevation, with parts broken away, of a first embodiment relating to a handrail;

FIG. 2 is a view in greater detail and to an enlarged scale, with parts broken away, of a portion of the system shown in FIG. 1;

. FIG. 3 is a view in cross section and to an enlarged scale on the line IIIIII of FIG. 1;

,FIG. 4 is a cross-sectional view similar to FIG. 3 but along the line IV--IV of FIG. 1;

FIG. 5 is a partial view similar to FIG. 3 but of a first variant of the invention; 7

FIG. 6 is a diagrammatic view in cross section of another variant which relates to the shape of the drive pulley flanges;

FIG. 7 is a diagrammatic view in cross section of a first variant of a moving device;

FIG. 8 is a view similar to FIG. 7 of a second variant of the moving device, and

FIG. 9 is a diagrammatic and perspective view of one use of the invention.

FIGS. 1-4 of the according drawings show how the drive system according to the invention can be used to embody a handrail for helping passengers getting on to a variable-speed travelator. The system mainly comprises a guide path or track 1 which extends along and above the travelator (not shown). Path 1 comprises two parallel rails 2 which are disposed opposite one another and which are mounted on evenly spacedapart posts 10 (FIG. 2); disposed therebetween are protective plates 3 forming a casing.

A number of moving bearing facilities or devices 4 which are independent of one another are disposed between the rails 2 and each comprise a support block 5 borne by a slide or carriage mainly comprising a yoke 7; on one side of the yoke cheeks are mounted two rollers 8 and on the other side is mounted a single roller 8 which is disposed between the lastmentioned two rollers 8. The rollers 8 run in the rails 2.

The yoke 7 bears the rotating member driving the moving member; in the example being considered, the rotating member is a pulley 11 rotatably mounted on a spindle 9 of yoke 7 and having two variable-spacing flanges 12, 13 whose internal surfaces are conical and rectilinear in shape. Flange 12 is secured by a pin 14 to a sleeve 15 rigidly secured to spindle 9. Flange 13 bears a ring 16 which is mounted with reduced friction on a bush 17 which extends from the flange l2 and which a key 18 secures rigidly to the sleeve 15. Flange 13 can therefore slide along bush 17 but, through the agency of a key 19, rotates solidly therewith. A return spring 21 which is coiled around the ring 16 and which bears on collar 22 of bush 17 biases flange 13 towards flange 12.

Associated with pulley 11 is a bearing surface which, in the example described, takes the form of a ramp 23 extending parallel to the rails 2 substantially in the central plane thereof. Ramp 23 is in cross section trapezoidal and its sides have the same inclination as the inner shape of the flanges 12, 13. The cross section of ramp 23 is constant, but the distance d thereof from the spindle 9 varies, with the path, between two extreme values-a maximum value, when the rolling radius of the pulley on the ramp 23 corresponds to d, (FIG. 3), and a minimum value (FIG. 4) at which the rolling radius of pulley 1 1 has the value d (FIG. 4).

So that ramp height may be varied relative to the path of the spindle 9, the ramp 23 is mounted on screw-threaded rods 24 whose height can be adjusted by nuts 25 and which engage in brackets 26 extending the posts 10. As can be seen in FIG. 1, the ramp 23 is cambered to give the changeover from the dimension d to the dimension d Pulley 11 is driven positively via a double chain 31 bearing on guides 32 borne by right-angle members 33 rigidly secured to the brackets 26. At the ends of the straight part of the slide guide path, chain 31 runs around drive wheels 34 mounted on shafts 35 running in bearings 36 rigidly secured to the posts (FIG. 3). At least one of the shafts 35 is a drive shaft and moves the chain 31 at a constant speed. Sleeve of pulley 11 has a gearwheel 37 of a diameter such that wheel 37 meshes with chain 31 whatever the position of the moving device 4 may be.

For the purpose envisaged in this particular case, the blocks 5 are interconnected by bellows 41 (FIG. 2), e.g. of leather, which are strong enough to take the weight of the users hands. Disposed in the bellows 41 are hooks 42 which are secured to the blocks 5 and interconnected by cables 43 long enough for consecutive devices 4 to move freely relatively to one another.

The drive system thus devised operates as follows:

The double chain 31 is driven at a constant speed by the drive wheels 34 in the direction indicated by an arrow F. The shaped ramp 23 is engaged between the pulley flanges 12 and 13. As the chain 31 moves in the direction of the arrow F, the pulley 11 rotates in the direction indicated by an arrow G, rolling on the ramp 23 without sliding and therefore displacing, in the direction indicated by an arrow II, the yoke 7 and the slide or carriage bearing the block 5.

If, as previously stated, d denotes the distance between the ramp 23 and the spindle 9 (such distance being somewhere between 11 and d and if R denotes the radius of the gearwheel 37 and and H denote the speeds of the chain 31 and device 4 in the directions F and II respectively, it is found by calculation that: r

H substantially =1? 11/ (d-R 1 corresponding to a hyperbolic movement pattern. Consequently, the speed of any device 4 is maximum when d is minimum-i.e., d and minimum when d=d If, therefore, the associated ramp 23 has a vertical shape such that the distance d is minimum and equal to d in the central part of the path between the two gearwheels 34, as is shown in FIG. 1, the speed Hof the devices 4 is greatest in the central part of the guide path. Of course, depending upon the vertical shape or profile of the ramp 23, a desired movement pattern can be imposed on the devices 4 to suit the requirements of a travelator. The bellows 41 adapt to variations in the spacing between the blocks 5 and are made of a mediumly stiff substance suitable to give support to the hand without nipping it.

In the variant shown in FIG. 5, the moving devices 4, instead of being driven by a chain 31, are driven by an individual motor 51 fitted with a reducer; this unit is mounted on one of the slide cheeks 7 and its gearwheel 52 engages with a gearwheel 53 of shaft 9. Motor 51 is energized via a trolley 54 rubbing on a conductor rail 55 disposed along the guide path and runs at a uniform speed throughout the path. Speed is varied in the manner hereinbefore described.

To alter the nature of the movement pattern given by formula (l), the invention comprises giving the flanges 12a, 13a of the pulley 11 a shape other than rectilinear, for instance, the curvilinear shape which is shown in FIG. 6 and which corresponds to a predetermined hyperbolic or exponential or some other function. In this event, the sides of the ramp 23 a are, with advantage, rounded tb facilitate the rolling of the pulley.

The invention also covers, instead of a pulley 11 having moving flanges, the use for the moving bearing device of a one-piece pulley 61 and an associated ramp 62 whose cross section can be varied along the path. correspondingly, in FIG. 7 the ramp 62 of circular cross section has a diameter and a height which can be varied in dependence upon the required movement pattern. When ramp 62 is of reduced diameter it is in the top position so that the pulley 61 is always in engagement with it. This is the case corresponding to the low speed movement. Of course, the yoke 7 can be mounted resiliently relatively to the moving bearing device to improve adhesion.

In the embodiment shown in FIG. 8, pulley 61 is mounted with provision for vertical clearance, through the agency of slots 65 in yoke 7a. In this event, a ramp 62 can be kept at a constant height, the small-diameter parts 620 assuming the same tangential plane as the remainder of the ramp.

In the embodiment shown in FIG. 9, there are two parallel drive systems; the moving support blocks 5, 5a thereof are driven, in the direction indicated by the arrow H, at the same instantaneous speed and are interconnected by a lattice 66 for holding the necks of a number of bottles 67 on a variablespeed conveyor 68 which is also moving in the direction of the arrow H. The advantage of this embodiment is that unstable articles can be placed on a variable-speed conveyor. Of course, the conveyor 68 of this embodiment can comprise developable elements driven by the moving bearing devices bearing the blocks 5, 5a.

The invention is not of course limited to the foregoing embodiments, which can be varied in many ways. For instance, in the embodiment shown in FIG. 8, springs 71 can keep the pulley 61 in engagement with the ramp 62. Similarly, the pulleys 1 1 could have two moving flanges.

I claim:

1 A variable-speed drive system comprising at least one device movable along a guide path, characterized in that the system comprises a rotating drive member which rolls on at least one bearing surface associated with the guide path; and means are provided to vary the rolling radius of the rotating member on the bearing surface in dependence upon the position of the moving device on its guide path.

2. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is a pulley having a fixed flange and a flange which can slide along the pulley axis of rotation and which is resiliently restored towards the fixed flange; and the bearing surface associated with the pulley is disposed at a variable distance from the pulley axis but is of unifonn width.

3. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is a one-piece pulley having flared flanges; and the bearing surface is of variable width, means being provided to engage the pulley with such surface along the path.

4. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is formed with a groove whose shape comprises two straight segments.

5. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is formed with a groove whose shape comprises two curvilinear segments.

6. A system as set forth in claim 1, characterized in that the moving device comprises a roller-fitted slide, and the guide path comprises two parallel iails on which the rollers bear, the slide bearing a yoke which is disposed between the two rails and which receives the rotating member driving the moving device.

7. A system as set forth in claim 6, characterized in that the guide path rails are borne by spaced uprights which also bear support members for the bearing surface, means also being provided to adjust the distance between the last-mentioned surface and the support member.

8. A system as set forth in claim 1, characterized in that the rotating member driving the moving device has a gearwheel which meshes with a driving linktype chain disposed along the guide path.

9. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is driven by a motor disposed thereon.

10. A system as set forth ih claim 8, characterized in that it comprises a number of moving devices whose gearwheels mesh with the same driving chain.

path and forming the elements of a variable-speed conveyor.

13. A system as set forth in claim 1, characterized in that it is associated with a similar system disposed parallel to it, the

moving devices being interconnected by transverse members which act as support members. 

2. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is a pulley having a fixed flange and a flange which can slide along the pulley axis of rotation and which is resiliently restored towards the fixed flange; and the bearing surface associated with the pulley is dispOsed at a variable distance from the pulley axis but is of uniform width.
 3. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is a one-piece pulley having flared flanges; and the bearing surface is of variable width, means being provided to engage the pulley with such surface along the path.
 4. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is formed with a groove whose shape comprises two straight segments.
 5. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is formed with a groove whose shape comprises two curvilinear segments.
 6. A system as set forth in claim 1, characterized in that the moving device comprises a roller-fitted slide, and the guide path comprises two parallel rails on which the rollers bear, the slide bearing a yoke which is disposed between the two rails and which receives the rotating member driving the moving device.
 7. A system as set forth in claim 6, characterized in that the guide path rails are borne by spaced uprights which also bear support members for the bearing surface, means also being provided to adjust the distance between the last-mentioned surface and the support member.
 8. A system as set forth in claim 1, characterized in that the rotating member driving the moving device has a gearwheel which meshes with a driving linktype chain disposed along the guide path.
 9. A system as set forth in claim 1, characterized in that the rotating member driving the moving device is driven by a motor disposed thereon.
 10. A system as set forth in claim 8, characterized in that it comprises a number of moving devices whose gearwheels mesh with the same driving chain.
 11. A system as set forth in claim 1, characterized in that it is used to form a handrail for a variable-speed travelator, the system comprising a number of moving devices disposed on the same endless guide path, the various moving devices being interconnected by extensible members such as bellows.
 12. A system as set forth in claim 1, characterized in that it comprises a number of devices movable along the same guide path and forming the elements of a variable-speed conveyor.
 13. A system as set forth in claim 1, characterized in that it is associated with a similar system disposed parallel to it, the moving devices being interconnected by transverse members which act as support members. 